Door furniture



E. J. HOLDEN DOOR FURNITURE Nov. 10, 1964 3 Sheets-Sheet 1 Filed Feb. 21, 1962 FIG.3.

3 Sheets-Sheet 2 E. J- HOLDEN DOOR FURNITURE Nov. 10, 1964 Filed Feb. 21, 1962 Nov. 10, 1964 E. J. HOLDEN 3,156,495

DOOR FURNITURE Filed Feb. 21, 1962 v s Sheets-Sheet 3 9a 5 ,aa 3l5 i r I HI 3s| 303/ sos if? v United States Patent 3,156,495 DOOR FURNITURE Ernest John Holden, 23 Welcombe Road, Stratford-upon-Avon, England Filed Feb. 21, 1962, Ser. *0. 174,761 Claims priority, application Great Britain, Apr. 13, 1961, 13,249/ 61; Dec. 29, 1961, 46,575/ 61 16 Claims. (Cl. 292-3363) This invention has reference to improvements relating to door furniture and is concerned particularly with door furniture of the kind in which there is associated with the operating lever, handle or knob a spring means for returning the said lever, handle or knob automatically to the locking position after turning for the purpose of unlocking.

In connection with door furniture of the said kind as constructed heretofore there is a libality to fracture of the return spring. Replacement of a broken return spring is difficult to effect with some existent constructions of door furniture and in other constructions where provision is made for the replacement of the return spring the construction is such that the permissive dimensions of the spring are limited with the consequence that the spring has to be made of such weak material that such springs readily fracture through Wear and/or corrosion.

The present invention has for its object to provide door furniture of the said kind which permits of the ready replacement of a return spring in the event of fracture but which also allows of the spring being made of such strong material that fracture is rendered unlikely.

Accordingly the invention consists of door furniture of the kind hereinbefore referred to in which the return spring is in the form of a spirally wound spring and in which the said spring is located concentrically around the internally disposed portion of the shank or boss of the operating lever handle or knob and readily accessible from the rear of the fixing plate rose or cover or from a part in fixed relationship therewith and in which one end of the said spring is anchored detachably to the lever handle or knob and in which the other end of the said spring is anchored detachably to the fixing plate rose or cover or to the part in fixed relationship therewith, the arrangement being such that the said spring is retained in position by its own tension whilst being readily removable if so required.

The invention also resides in door furniture constructed, arranged and adapted for use substantially as will be described hereinafter.

Embodiments of the invention will now be described with particular reference to the accompanying drawings wherein:

FIGURE 1 is a front elevation, partly broken away, of door furniture in accordance with one of the said embodiments of the invention showing the lever handle and associated components occupying the locking position,

FIGURE 2 is a rear view of FIGURE 1 with part of the lever handle broken away,

FIGURE 3 is a section on the plane indicated by the line 33 in FIGURE 2 looking in the direction of the arrows to the said line,

FIGURE 4 is a fragmentary view in section taken on the plane indicated by the line 4-4 FIGURE 2 looking in the direction of the arrows to the said line FIGURE 5 is a front elevation, partly broken away, of door furniture in accordance with another embodiment of the invention with the lever handle and associated components occupying the locking position,

FIGURE 6 is a fragmentary rear View of FIGURE 1 on an enlarged scale,

FIGURE 7 is a fragmentary end view of FIGURE 2 partly in elevation and partly in vertical section,

FIGURE 8 is a perspective rear View on the same scale as FIGURES 5 and 6 showing the flat spirally wound spring removed from the remainder of the door furniture without involving dismantling of the assembled parts thereof,

FIGURE 9 is a fragmentary view looking from the rear of yet another embodiment of the invention showing the lever handle and associated components occupying the locking position, and

FIGURE 9a is a vertical section taken on the plane indicated by the lines 9a9a, FIGURE 9 looking in the direction of the arrows.

According to the embodiment of the invention as illustrated in FIGURES 1 to 4 the improved door furniture incorporates a lever handle 10 having a cylindrical boss 101 provided therein with the usual square hole 102 for the reception of the lock spindle 11. This boss 101 is turnably mounted in a bush 12 conveniently made of the synthetic plastics materials known as nylon. The bush 12 in turn is housed within a central hole in the usual domed rose or cover 13 and in the fixing plate 14. Located within the customary recess 141 in the rear of the fixing plate 14 is a sheet metal washer 15 of known proprietary make and known as a star lock washer. This washer 15 is provided with an angular portion 151, the sides 151a and 15122 whereof co-operate with stops 142 and 143 formed on the inner side of the fixing plate 14 for limiting the movement permitted to the lever handle 10 in known manner.

Housed within the recess 152 in the rear of the washer 15 is a flat spiral spring 16 made of heavy gauge wire one end of which is cranked as at 161 for engagement within the slot 164 in the boss of the lever handle 10 whilst the other end is cranked as at 162 for engagement within a hole 144 formed in a boss 145 on the inside of the fixing plate 14.

The spring 16 is retained in position within the washer 15 by virtue of its own tension assisted as shown by tongues 153 bent out of the said Washer 15.

It may be remarked here that, although preferable, the provision of tongues 153 for assisting in retaining the spring 16 in position is not essential as in general the tension in the spring will sutiice for the said purpose. The use of the tongues 153 however safeguards any tendency to outward bulging of the spring 16.

Alternatively instead of providing the boss 145 with a hole 144 for the anchorage of the cranked end 162 of the spring 16 the said end of the spring 16 may be held by a bent over tag or other means attached to the fixing plate 14 which would permit the spring 16 to be sprung into position and held firmly by the tension thereof.

In the case (not illustrated) where the invention is employed with door furniture in which the rose or cover also serves as the fixing plate the spring 16 is housed within the customary recess in the rear of the rose or cover one end of the spring then being anchored to the boss of the lever handle or knob 10 whilst provision is made for anchoring the other end of the spring 16 to the rose or cover.

It will be appreciated that when the lever handle is moved clockwise from the position seen in FIGURE 1, i.e. from the locking to the unlocking position the spring 16 is stressed but permits the movement of the lever handle 10 being continued until the side 151b of the angular portion 151 of the washer 15 contacts the stop 141 see dotted line positions in FIGURE 2.

When this obtains unlocking is complete and on the subsequent release of the lever handle 10 said lever handle 10 returns to the locking position as determined by abutment of the opposite side 151a of the angular portion 151 of the washer 15 with the abutment 142.

It will be appreciated that by forming the spring 16 as a spiral and arranging the said spring 16 concentrically around the internally disposed portion of the boss 101 of the lever handle 10 the spring 16 may be made of a relatively large outside diameter and of a heavy gauge wire so that liability to fracture through wear and/or corrosion is greatly reduced compared with that of return springs of existent practice.

Further it will be appreciated that in the event of frac- 'ture of the spring the spring 16 can readily be replaced.

According to the embodiment of the invention as illustrated in FIGURES to 8 the boss of the lever handle therein designated by the reference numeral 21 is provided with a cylindrical portion 251 which is turnably mounted within a circular hole formed in the centre of a flanged sheet metal fixing plate 21 of conventional construction. The cylindrical portion Zill continues in a rearwardly directed extension 292 which is provided on either side with flats 263 as is clearly seen in FIG- URE 4. intermediate its ends the boss extension 292 is provided on each side with a groove 2%, see FIGURE 8, as and for a purpose to be described hereinafter.

Pressed within the fixing plate 21 on the rear side thereof is a flanged sheet metal insert 22 having therein a hole 221 which is caused to register with the hole 211 in the fixing plate 21 in which the cylindrical boss 231 is turnably mounted.

The side flanges 222 of the insert 22 are in a press fit contact with the inner surfaces of the side flanges 213 of the fixing plate 21.

At the lower end, as viewed in the drawings, the insert 22 is provided with a flange 223 provided at each end thereof with undercuts 22 see FIGURE 8.

After the passage of the cylindrical boss 261 through the hole 211 in the fixing plate 21 and the hole 221 in the insert 22 there is passed onto the boss extension 202 from the rear a sheet metal plate 23 hereinafter termed the stop plate 23 which is provided with a hole incorporating flats so that the said insert may fit over the boss extension 202. The stop plate 23 is provided at its upper end as viewed in the drawings with a pair of oppositely inclined faces 232 for co-operation in a known manner with the side flanges 222 of the insert 22 for determining the degree of movement to be permitted to the operating lever 20.

The stop plate 23 is provided also with oppositely disposed tongues 233 which engage within an elongated slot 205 in the boss extension 2-32 for keeping the stop plate 23 on the said boss extension 262.

After the assembly of the stop plate 23 on the boss extension 262 the assembly is retained in unitary assembly condition by springing a clip 24 into the grooves 294- in the side of the boss extension 262, see FIGURE 8. This clip 24 is provided with an outwardly projecting bridging limb 241 for engagement by the fingers or a tool and the side limbs 242 are provided at outer ends with outwardly turned portions 24-3, see FIGURES 6 and 8.

Adapted to be fitted within the confines of the insert 22 is a spiral spring 26 made of heavy gauge wire one end of which is cranked as at 261 for engagement with the slot 205 in the boss extension 202. The other end portion of the spring 26 is provided with a straight section 262 which terminates in a hook 263 so that the spring 26 may be anchored to the insert 22 by engaging the bend 264 at the junction of the straight section 262 in one of the undercuts 224 and engaging the hook 263 with the opposite undercut 224.

The spring 26 is seated in the insert 22 so that the turn 265 thereof is located below the upwardly turned ends of the clip 24.

It is pointed out however that although this manner of engaging the spring 26 with the boss extension 202 provides an additional means for securing the spring 26 in position this is purely an additional security measure as the spring 26 when fixed as aforesaid will remain in position under its own tension.

In the event of the failure or need for replacement of a spring 26 the faulty spring 26 may be removed without dismantling the assembly by disengaging the cranked end 261 from within the slot 2-93 and then disengaging the hook 263 from the relevant undercut 224 leaving the remaining parts in unitary assembly as is seen in FIG- URE 8.

The replacement spring 26 may be fitted without requiring dislodgment of any of the other parts of the assembly.

According to the embodiment of the invention as illustrated in FIGURES 9 and 9a, the insert incorporated in the construction described with reference to FIGURES 5 to 8 is eliminated and the flanged sides of the fixing plate 31 which conveniently is a casting are provided with internal oppositely disposed abutments 315 for cooperation with the stop plate 33 to be referred to hereinafter. The shank or boss 3% of the lever handle or knob in the figures designated by the reference numeral 30 is of non-circular configuration and is adapted to have mounted thereon an annular bearing bush 36 which is turnable within the hole 311 in the fixing plate. Mounted on the portion of the shank or boss 302 which is internally disposed when the door furniture is assembled is the hub 334- of a stop plate 33 of similar configuration to that of the stop plate 23 in the construction illustrated in FIG- URES 5 to 8.

The hub 334 is provided with a hole of complementary shape and size to that of the shank or boss 302 so that the said hub 33 may be threaded on to the shank or boss 362 and thereby become non-rotatable thereon.

The shank or boss 302 is formed with an elongated vertical slot whilst the hub 33-: is provided with a hole 335 which is in register with the relevant portion of the slot 305 when the stop plate 33 has been positioned correctly on the shank or boss 302.

Adapted to be inserted through the said hole 335 and engaged in the appropriate portion of the slot 305 is the cranked end 361 of a spirally wound conical spring which is arranged substantially concentrically around the hub 334 the other end of the spring 35 being hooked into engagement with an anchorage block 313 east integrally with the fixing plate 31 and which projects outwardly therefrom.

The bearing bush 37 and the stop plate 33 including the hub 334 are made of a material having a low co-efiicient of friction, conveniently the material known as nylon. in this latter eventuality the stop plate 33 and the hub 334 may be formed as an integral moulding.

The door furniture according to this last mentioned embodiment of the invention is assembled by first passing the annular bearing bush 37 over the shank or boss 302 and then threading the said bush 37 into the hole in the fixing plate 31 until the said annular bush 37 contacts the wall 316 bounding the hole 311 in the fixing plate 31. The hub 334 of the stop plate 33 is then threaded over the internally projecting portion of the shank or boss 302 and the assembly secured permanently by spin-riveting the end of the shank or boss 302 as at 304.

Subsequently the relevant end of the spring 36 is passed through the hole 335 in the hub 334 of the stop plate 33 and engaged within the registering portion of the slot 305. The other end of the spring 36 is hooked into engagement with the anchorage block 313.

Again, in the event of the failure of or need for replacement of a faulty spring 36 this may be done without disturbing in any way the rest of the assembly by disengaging the cranked end 361 of the spring 36 from the slot 365 and hole 335 and unhooking the other end of the spring 36 from the anchorage block 313.

In both the embodiments last described it will be appreciated that the springs 26, 36, may be made also of relatively large outside diameter and of a heavy gauge wire so that liability to fracture through wear and/or corrosion is greatly reduced compared with the springs of existent practice.

If desired the springs 16, 26, 36 may be anchored to the stop plates 13, 23, 33 as the case may be instead of to the shank or boss, 202, 302 and the said springs 16, 26, 36 may be fiat with the turns uniplanar or the turns may be multi-planar.

I claim:

1. Door furniture incorporating a mounting means for fixing to a door, an actuating means turnably mounted relatively to said mounting means and having a portion thereof disposed internally of said mounting means, abutments associated with said mounting means, a stop member mounted on but non-rotatable relatively to said portion for determining in conjunction with the abutments aforesaid the degree of movement to be permitted to the actuating means, a spirally wound return spring arranged to encircle the internally disposed portion of the actuating means and to be exposed when viewed from the rear of the mounting means and thereby rendered readily accessible from the rear of the mounting means, a fixed anchorage associated with the mounting means which is exposed when viewed from the rear, said spring having one end thereof anchored detachably to the said actuating means and the other end thereof anchored detachably to a said fixed anchorage and thereby being adapted for effecting the return of the actuating means automatically to the locking position after the actuation of said actuating means to perform an unlocking operation, the arrangement being such that the said return spring normally is retained in position by its own tension whilst being readily removable if so required by detaching the appropriate end of the spring from one anchorage and then detaching the other end of the return spring from the other anchorage and then withdrawing the spring over the internally disposed portion of the actuating means Without involving disturbance of any other component of the assembly.

2. Door furniture incorporating a mounting means for fixing to a door an actuating means turnably mounted relatively to said mounting means and having a portion thereof disposed internally of said mounting means, abutments associated with said mounting means, a stop member mounted on but non-rotatable relatively to said portion for determining .in conjunction with the abutments aforesaid the degree of movement to be permitted to the actuating means, means for securing said stop memher on the portion aforesaid so that the mounting means, actuating means and stop member form a unitary assembly but which admits of the detachment of the stop member if required and a spirally wound return spring arranged to encircle the internally disposed portion of the actuating means and to be exposed when viewed from the rear of the mounting means and thereby rendered readily accessible from the rear mounting means, a fixed anchorage associated with the mounting means which is exposed when viewed from the rear said spring having one end thereof anchored detachably to the actuating means and the other end thereof anchored detachably to said fixed anchorage and thereby being adapted for effecting the return of the actuating means automatically to the locking position after the actuation of said actuating means to perform an unlocking operation the arrangement being such that the said return spring normally is retained in position by its own tension whilst being readily removable if so required by detaching the appropriate end of the spring from one anchorage and then detaching the other end of the return spring from the other anchorage and then withdrawing the return spring over the internally disposed portion of the actuating means without involving disturbance of any other component of the assembly.

3. Door furniture incorporating a mounting means for fixing to a door, an actuating means turnably mounted relatively to said mounting means and having a portion thereby disposed internally of said mounting means, abutments, associated with said mounting means, a stop member mounted on but non-rotatable relatively to said portion for determining in conjunction with the abutments aforesaid the degree of movement to be permitted to the actuating means, means for securing said stop member on the portion aforesaid so that the mounting means, actuating means and stop member form a permanent unitary assembly and a spirally wound return spring arranged to encircle the internally disposed portion of the actuating means and to be exposed when viewed from the rear of the mounting means and thereby rendered readily accessible, a fixed anchorage associated with the mounting means which is exposed when viewed from the rear, said spring having one end thereof anchored detachably to the actuating means and the other end thereof anchored detachably to a said fixed anchorage and thereby adapted for effecting the return of the actuating means automatically to the locking position after the actuation of said actuating means to perform an unlocking operation the arrangement being such that the said return spring normally is retained in position by its own tension whilst being readily removable if so required by detaching the appropriate end of the spring from one anchorage and then detaching the other end of the return spring from the other anchorage and then withdrawing the return spring over the internally disposed portion of the actuating means without involving disturbance of any other component of the assembly.

4. Door furniture incorporating a mounting means for fixing to a door, an actuating means turnably mounted relatively to said mounting means and having a portion thereof disposed internally of said mounting means, abutments associated with said mounting means, a stop member mounted on but non-rotatable relatively to said portion for determining in conjunction with the abutments aforesaid the degree of movement to be permitted to the actuating means, spring means for securing said stop member on the portion aforesaid so that the mounting means, actuating means and stop member form a unitary assembly and a spirally wound return spring arranged to encircle the internally disposed portion of the actuating means and to be exposed when viewed from the rear of the mounting means and thereby rendered readily accessible from the rear mounting means, a fixed anchorage associated with the mounting means which is exposed when viewed from the rear said spring having one end thereof anchored detachably to the actuating means and the other end thereof anchored detachably to said fixed anchorage and thereby being adapted for effecting the return of the actuating means automatically to the locking position after the actuation of said actuating means to perform an unlocking operation the arrangement being such that the said return spring normally is retained in position by its own tension whilst being readily removable if so required by detaching the appropriate end of the spring from one anchorage and then detaching the other end of the return spring from the other anchorage and then Withdrawing the return spring over the internally disposed portion of the actuating means without involving disturbance of any other component of the assembly.

5. Door furniture incorporating a mounting means for fixing to a door, an actuating means turnably mounted relatively to said mounting means and having a portion thereof disposed internally of said mounting means, abutments associated with said mountnig means, a stop member mounted on but non-rotatable relatively to said portion for determining in conjunction with the abutments aforesaid the degree of movement to be permitted to the actuating means, detachable spring means for securing said stop member on the portion aforesaid so that the mounting means, actuating means and stop member form a unitary assembly but which may be detached for dismantling of the said assembly if required and a spirally wound return spring arranged to encircle the internally disposed portion of the actuating means and to be exposed when viewed from the rear of the mounting means and thereby rendered readily accessible from the rear mounting means, a fixed anchorage associated with the mounting means which is exposed when viewed from the rear said spring having one end thereof anchored detachably to the actuating means and the other end thereof anchored detachably to said fixed anchorage and thereby being adapted for effecting the return of the actuating means automatically to the locking position after the actuation of said actuating means to perform an unlocking operation the arrangement being such that the said return spring normally is retained in position by its own tension whilst being readily removable if so required by detaching the appropriate end of the spring from one anchorage and then detaching the other end of the return spring from the other anchorage and then withdrawing the return spring over the internally disposed portion of the actuating means without involving disturbance of any other component of the assembly.

6. Door furniture incorporating a mounting means for fixing to a door, an actuating means turnably mounted relatively to said mounting means and having a portion thereof disposed internally of said mounting means, abutments associated with said mounting means, a stop member mounted on but non-rotatable relatively to said portion for determining in conjunction with the abutments aforesaid the degree of movement to be permitted to the actuating means, spring means for securing said stop member on the portion aforesaid so that the mounting means actuating means and stop member form a unitary assembly, a spirally wound return spring arranged to encircle the internally disposed portion of the actuating means and to be exposed when viewed from the rear of the mounting means and thereby rendered readily accessible from the rear mounting means, a fixed anchorage associated with the mounting means which is exposed when viewed from the rear said spring having one end thereof anchored detachably to the said actuating means and the other end thereof anchored detachably to said fixed anchorage and thereby being adapted for effecting the return of the actuating means automatically to the locking position after the actuation of said actuating means to perform an unlocking operation, the arrangement being such that the said return spring normally is retained in position by its own tension with the assistance of the spring means whilst being readily removable if so required by detaching the appropriate end of the spring from one anchorage and detaching the other end of the return spring from the other anchorage and then withdrawing the spring from engagement with the spring means and over the internally disposed portion of the actuating means without involving disturbance of any other component of the assembly.

7. Door furniture comprising a fixing plate for fixing to a door, a flanged insert located within said fixing plate at the rear thereof with the flanges of the said insert in contact with the perimeter wall of the fixing plate, an actuating means incorporating a boss which is turnably mounted in the fixing plate, a stop plate cooperating with the sides of the insert for determining the degree of movement to be permitted to the actuating means, non-rotatably mounted on the internally disposed portion of the boss of the actuating means, means for retaining the said stop plate in position on the said boss and a spirally wound return spring arranged concentrically around the boss, and to be exposed when viewed from the rear of the fixing plate and to be rendered accessible from the rear of the fixing plate, a fixed anchorage associated with the fixing plate which is exposed when viewed from the rear, said spring having one end thereof anchored detachably to the boss and the other end of which is to be anchored detachably to the said fixed anchorage and thereby being adapted for effecting the return of the actuating means automatically to the locking position after the actuation of said actuating means to perform an unlocking operation, the arrangement being such that the said return spring normally is retained in position by its own tension whilst being readily removable if so required by detaching the appropriate end of the spring from one anchorage and then detaching the other end of the return spring from the other anchorage and then withdrawing the spring over the internally disposed portion of the actuating means without involving disturbance of any other component of the assembly.

8. Door furniture comprising a flanged fixing plate for fixing to a door, an actuating means incorporating a boss, an annular bearing bush made of a material of low co-efficient of friction which is mounted in a hole in the fixing plate and which serves as a bearing from the said boss, a stop plate of similar material to the annular bearing bush non-rotatably mounted on the boss and retained thereon in unitary assembly with the fixing plate and actuating means said stop plate serving in conjunction with the flanges of the fixing plate to determine the degree of movement to be permitted to the actuating means and a spirally wound return spring arranged concentrically around the boss and to be exposed when viewed from the rear of the flanged fixed plate and to be rendered readily accessible from the rear of the flanged fixed plate, a fixed anchorage associated with the flanged fixing plate which is exposed when viewed from the rear said spring having at one end thereof anchored detachably to the boss and the other end be anchored detachably to the said fixed anchorage and thereby being adapted for effecting the return of th actuating means automatically to the locking position after the actuation of said actuating means to perform an unlocking operation, the arrangement being such that the said return spring normally is retained in position by its own tension whilst being readily removable if so required by detaching the appropriate end of the spring from one anchorage and detaching the other end of the return spring from the other anchorage and then withdrawing the spring over the internally disposed portion of the actuating means Without involving disturbance of any other component of the assembly.

9. Door furniture as claimed in claim 1 in which the spirally wound spring is made from wire and in which one end thereof is cranked for engagement in an aperture in the internally disposed portion of the actuating means and in which the other end of the spring is adapted for a hook engagement with the fixed anchorage.

10. Door furniture as claimed in claim 1 in which the spirally wound return spring is made from wire and in which the turns thereof are uniplanar.

11. Door furniture as claimed in claim 1 in which the spirally wound return spring is made from wire and in which the turns thereof are multi-planar.

12. Door furniture as cla' ned in claim 3 in which the mounting means, actuating means and stop plate are held together as a permanent assembly by spin-riveting the end of the internally disposed portion of the actuating means after the assembly has been made.

13. Door furniture as claimed in claim 3 in which the spring means for securing the stop member on the internally disposed portion of the actuating means is in the form of a star lock washer.

14. Door furniture as claimed in claim 4 in which the spring means for securing the stop member detachably in the internally disposed portion of the actuating means is in the form of a jawed spring clip and in which the side limbs of the said clip are adapted to be accommodated in complementary grooves found in the sides of the internally disposed portion of the actuating means.

15. Door furniture as claimed in claim 8 in which the stop plate incorporates an integral hub for threading on to the internally disposed portion of the actuating means.

16. Door furniture as claimed in claim 8 in which the stop plate incorporates an integral hub for threading on to the internally disposed portion of the actuating means and in which the said stop plate and hub are formed from synthetic plastic material having a low co-efficient of friction.

References Cited by the Examiner UNITED STATES PATENTS 1,899,997 3/33 Sullivan 292r-357 X FOREIGN PATENTS 597,382 1/48 Great Britain. 708,383 5/54 Great Britain. 708,869 5/54 Great Britain. 1,084,624 7/54 France.

ALBERT H. KAMPE, Primary Examiner.

JOSEPH D. SEERS, Examiner. 

1. DOOR FURNITURE INCORPORATING A MOUNTING MEANS FOR FIXING TO A DOOR, AN ACTUATING MEANS TURNABLY MOUNTED RELATIVELY TO SAID MOUNTING MEANS AND HAVING A PORTION THEREOF DISPOSED INTERNALLY OF SAID MOUNTING MEANS, ABUTMENTS ASSOCIATED WITH SAID MOUNTING MEANS, A STOP MEMBER MOUNTED ON BUT NON-ROTATABLE RELATIVELY TO SAID PORTION FOR DETERMINING IN CONJUNCTION WITH THE ABUTMENTS AFORESAID THE DEGREE OF MOVEMENT TO BE PERMITTED TO THE ACTUATING MEANS, A SPIRALLY WOUND RETURN SPRING ARRANGED TO ENCIRCLE THE INTERNALLY DISPOSED PORTION OF THE ACTUATING MEANS AND TO BE EXPOSED WHEN VIEWED FROM THE REAR OF THE MOUNTING MEANS AND THEREBY RENDERED READILY ACCESSIBLE FROM THE REAR OF THE MOUNTING MEANS, A FIXED ANCHORAGE ASSOCIATED WITH THE MOUNTING MEANS WHICH IS EXPOSED WHEN VIEWED FROM THE REAR, SAID SPRING HAVING ONE END THEREOF ANCHORED DETACHABLY TO THE SAID ACTUATING MEANS AND THE OTHER END THEREOF ANCHORED DETACHABLY TO A SAID FIXED ANCHORAGE AND THEREBY BEING ADAPTED FOR EFFECTING THE RETURN OF THE ACTUATING MEANS AUTOMATICALLY TO THE "LOCKING" POSITION AFTER THE ACTUATION OF SAID ACTUATING MEANS TO PERFORM AN "UNLOCKING" OPERATION, THE ARRANGEMENT BEING SUCH THAT THE SAID RETURN SPRING NORMALLY IS RETAINED IN POSITION BY ITS OWN TENSION WHILST BEING READILY REMOVABLE IF SO REQUIRED BY DETACHING THE APPROPRIATE END OF THE SPRING FROM ONE ANCHORAGE AND THEN DETACHING THE OTHER END OF THE RETURN SPRING FROM THE OTHER ANCHORAGE AND THEN WITHDRAWING THE SPRING OVER THE INTERNALLY DISPOSED PORTION OF THE ACTUATING MEANS WITHOUT INVOLVING DISTURBANCE OF ANY OTHER COMPONENT OF THE ASSEMBLY. 